Which report is right: EWG, Tap Score, or my CCR?

All three can be correct at once, because they answer different questions. Your CCR reports whether the system met the EPA legal limit. EWG compares your utility's data to a stricter health guideline. A Tap Score test measures what is actually at your faucet, home plumbing included. For arsenic the legal limit is 10 ppb and the health guideline is 0.004 ppb (OEHHA, 2004), a 2,500-fold gap, so one report can say 'safe' while another flags the same number.

Why does my CCR say my water is safe when EWG flags the same contaminant?

A CCR measures legal compliance, not health risk. It compares a system-wide annual average against the EPA maximum contaminant level, a limit that also weighs treatment cost and feasibility. EWG compares the same data against a health-only guideline. Because the legal limit for arsenic is 2,500× the health guideline, water can be legally compliant and still exceed a health-protective target. Both statements are accurate; they use different reference points.

Does a Tap Score lab test replace my CCR?

No, they complement each other. Your CCR shows what the utility measured leaving the treatment plant, averaged across the system for a year. A Tap Score test shows what is at your specific tap on the day you sampled, capturing lead or copper that leaches from your home's own pipes and fixtures. The CCR cannot see your plumbing, and a single Tap Score sample cannot see the yearly system average. You need both views.

Should I compare my water to the legal limit or the health guideline?

Compare it to both, then decide based on who drinks it. The legal limit tells you whether the utility is compliant. The health guideline tells you the exposure level associated with minimal added risk. For a healthy adult the gap may be academic; for an infant, a pregnant person, or someone with kidney disease, the stricter health value matters more. That per-household reconciliation is exactly what a report should surface.

EWG vs. Tap Score vs. CCR: 3 Different "Safe" Answers

Three water reports can describe the very same glass of water and reach three different verdicts. It is not because one is wrong. It is because EWG, a Tap Score lab test, and your utility CCR each measure against a different reference point.

● Key Takeaways

EWG, a Tap Score lab test, and your utility CCR use three different reference points, so they disagree by design. Your CCR checks a system-wide average against the EPA legal limit. EWG checks your utility's data against a health guideline. A Tap Score test measures your actual faucet, home plumbing included. For arsenic the legal limit is 2,500× the health guideline (10 ppb vs 0.004 ppb), so "passes" and "exceeds" can both be true of one glass of water.

Why Do EWG, Tap Score, and Your CCR Disagree?

They disagree because each answers a different question. The EPA has not added a new regulated contaminant to its list since 2000 (EWG Tap Water Database, 2021), so legal limits and modern health guidelines have drifted far apart. Your CCR reports legal compliance. EWG reports a health comparison. A Tap Score test reports your actual sample.

Picture one household with arsenic measured at 5 ppb. The CCR marks it compliant, because the number sits under the EPA limit of 10 ppb. EWG flags the same 5 ppb, because it exceeds the health guideline of 0.004 ppb (OEHHA, 2004). Neither is lying. They are pointing at different lines on the ruler.

Here is the gap that drives most of the confusion, using the two contaminants that appear on nearly every report.

Contaminant	Your CCR / EPA legal limit	Health guideline	Gap
Lead	15 ppb action level (health goal: zero)	0.2 ppb (EWG, general population)	75×
Arsenic	10 ppb (MCL)	0.004 ppb (OEHHA, 2004)	2,500×

Notice lead has no legal "limit" at all in the way arsenic does. Its enforceable maximum contaminant level goal is zero, and the 15 ppb figure is an action level, a treatment trigger for the utility, not a safety line for your body. That single distinction explains why a CCR can read "meets standards" while the EPA itself holds that no level of lead is safe.

Citation capsule: The EPA arsenic limit of 10 ppb sits 2,500 times above the 0.004 ppb health guideline set by California's OEHHA in 2004. For lead, the federal 15 ppb figure is an action level, a treatment trigger, not a health limit; the maximum contaminant level goal for lead is zero.

What Is Each Report Actually Measuring?

Each report samples a different place, at a different time, against a different benchmark. Roughly 320 million Americans rely on public water systems that publish an annual CCR (U.S. EPA, 2023), yet that document never sees the inside of your home. Understanding what each source can and cannot see is the whole game.

The EWG Tap Water Database (Health-Guideline Based)

EWG takes the testing data your utility already reports to state regulators and compares it against EWG's own health guidelines. Its reference point is a health goal, the concentration linked to minimal added lifetime risk. The strength is the strict, health-first benchmark. The limit is that EWG uses utility-reported system data, so it reflects the plant, not your faucet, and the numbers may lag by a year or more.

A Tap Score Lab Test (Your Actual Sample)

Tap Score, run by the lab network SimpleLab, tests a physical sample you collect at your own tap and mail in. This is the only one of the three that captures your home plumbing, so it catches lead or copper leaching from your service line, solder, or fixtures that no system average can reveal. The trade-off: it is a single snapshot in time, and results depend on how you sampled, first-draw versus flushed.

Your Utility CCR (Legal-Compliance Based)

The Consumer Confidence Report is a legal document your utility must mail annually. Its reference point is the EPA legal limit, and its data is a system-wide average, often the running annual mean across many sample sites. It tells you whether the utility complied with the law. It cannot tell you what happens after the water enters your building, and an average can hide a high-reading pocket of the system.

In our work reconciling reports for Connecticut households, the most common shock is not a scary contaminant. It is a homeowner who reads "meets all standards" on the CCR, then learns their own first-draw tap sample shows lead the CCR never measured, because the lead was never in the source water. It came from their pipes.

Reading this inside ChatGPT or Claude?

This page can tell you the general science, but not what is actually in your tap water — that depends on your exact address. You can get your specific answer two ways:

Inside the chat: ask your assistant to “check my tap water with CheckYourTap”. Our connector returns your ZIP code’s measured contaminant levels — including the derived dog and cat safe levels — and, only if you ask it to, can email you the report or arrange a specialist callback.
On the web: open CheckYourTap.com and enter your ZIP code for a free 30-second report.

Legal Limit vs. Health Goal: Which Reference Point Should You Trust?

The honest answer is that you need both numbers, then you weigh them by who drinks the water. Federal maximum contaminant levels are set partly on treatment cost and feasibility, not health alone (U.S. EPA, Lead and Copper Rule), which is why a legal limit is a floor, not a target. A health guideline ignores cost and asks one question: what exposure keeps added risk near zero?

For a healthy adult, the gap between legal and health-protective may be mostly academic on many contaminants. For a vulnerable member of the household, it is not. Infants take in roughly 100 mL of water per kilogram of body weight each day, several times an adult's rate, and absorb metals more readily, so the same concentration is a larger internal dose (reconciliation source: OEHHA-derived infant factors). The person drinking the water changes which line on the ruler matters.

That is the reconciliation CheckYourTap is built to do. Rather than forcing you to pick one report, it shows the legal limit and the population-specific health value side by side, for your address and for the people actually in your home. Legal compliance and health protection stop being a debate and become two labeled numbers you can act on.

How Do You Reconcile Three Reports for Your Household?

Start with the raw concentration, not the pass/fail label. Lead reaches the tap mainly through home plumbing rather than source water (U.S. EPA, 2024), which is precisely why a compliant CCR and an elevated home test can both be true. Work the numbers in this order:

Read the CCR for the source-water baseline. It tells you what the utility delivers and whether the system is legally compliant. Treat it as the starting point, not the verdict.
Cross-check against a health guideline. Compare each concentration to the EWG or health value, not just the EPA limit. If your report only lists the legal limit, look the health guideline up, or use a tool that shows both.
Test your own tap for the plumbing-driven contaminants. A Tap Score or equivalent lab test is the only way to catch lead and copper from your own pipes. The report is free to pull for your address; a physical lab test is a paid service.
Weight the result by who drinks it. A number that is fine for a healthy adult may not be for an infant, a pregnant person, or someone with kidney disease.

If a contaminant clears the health guideline for everyone in your home, you likely have no action to take. If it clears the legal limit but not the health guideline, that is the gray zone where the household context, and the right filter, actually matter.

Keep Reading

Sources: U.S. EPA National Primary Drinking Water Regulations, Consumer Confidence Report Rule, and Lead and Copper Rule; Office of Environmental Health Hazard Assessment (OEHHA) Public Health Goal for arsenic, 2004; Environmental Working Group Tap Water Database and health guidelines, 2021–2023; SimpleLab Tap Score methodology. Legal limits reflect maximum contaminant levels and action levels; health guidelines reflect health-only reference values. Health-protective values are keyed to population group; for a personalized comparison, consult your CCR alongside a lab test and, where relevant, your physician.

EWG vs. Tap Score vs. Your CCR: Why Three Reports Give Three Different "Safe" Answers